Sulfuric acid leaching of polymetallic Abu Zeneima gibbsite-shale

The gibbsite shales belonging to the Paleozoic sequence of sedimentary rocks occurring at the Abu Zeneima area in SW Sinai Egypt has been found to host several economic metal values. These include Al, Cu, Zn, Co, Ni, REE, and U beside several Mn minerals. In this work, the ore was subjected to sulfuric acid leaching to maximize extraction of these metal values. The optimum leaching conditions were 800 g/L acid with a Solid/Liquid ratio of 1/2 at 100 °C for 4 h and using an ore size of − 60 mesh. Under these conditions, it was possible to achieve high leaching efficiencies with complete leaching of Al together with 93.0% Cu, 58.6% Zn, 69.0% Co, 92.6% Ni and 84.4% U. Extension of the leaching time to 8 and 12 h significantly improved the leaching efficiencies of Co and Zn to 91.0% and 84.0% respectively.